Image positioning technology is to calculate a pose based on one image or a group of images. This technology can be applied in robot navigation, route planning, digital tourism, virtual reality, etc., and can also be applied in areas where GPS (Global Positioning System) cannot work, such as indoor and underground. Compared with the positioning technology based on Bluetooth and WiFi (Wireless Fidelity), the image positioning technology does not rely on professional equipment and has low implementation cost.
In the related art, there are mainly two methods for image positioning. One method is based on image retrieval, which searches for an adjacent image of a query image in a database, and takes a position thereof as its own position. The other method is based on 3D reconstruction in combination with image-point cloud (2D-3D) matching. This method acquires a large number of plane images about a target scene in advance, performs 3D reconstruction offline to obtain a 3D feature point cloud of the scene, and in an online phase, extracts features of the query image and performs 2D-3D matching between the features of the query image and the 3D feature point cloud to estimate a pose of a target camera based on the matching result.
However, there are problems for the above methods. For the method based on image retrieval, since 3D information is not fully utilized, it can only be applied to cases where an attitude difference between the query image and library images is small, and positioning accuracy of this method is not better than positioning accuracy and sampling interval of the library image. Compared with the method based on image retrieval, the above-mentioned second method can obtain a more accurate positioning result, but its 3D reconstruction algorithm can only be applied in a plane camera, and limited to a small field of view of the plane camera, it usually needs to change multiple angles at the same position to obtain a large set of plane images for 3D reconstruction, and thus cost of reconstruction is high, such as quantity of acquisition is large and quantity of calculation is large.